Single line control module for well tool actuation

ABSTRACT

A single line control module for well tool actuation. A well tool control system includes an actuator, a control module for controlling pressure applied to the actuator, and a single line extending between the control module and a remote location, elevated pressure being applied to the line and exhausted from the line at the remote location to operate the actuator. Another well tool control system includes an actuator having first and second chambers, a line for applying elevated pressure to the actuator to operate the actuator, and a control module including an accumulator, and a valve. The valve has a first position in which the line is connected to the first chamber and the accumulator is connected to the second chamber, and a second position in which the line is connected to the second chamber and the accumulator is connected to the first chamber.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit under 35 USC §119 of thefiling date of International Application No. PCT/US2005/016971, filed onMay 13, 2005, the entire disclosure of which is incorporated herein bythis reference.

BACKGROUND

The present invention relates generally to equipment utilized andmethods performed in conjunction with a subterranean well and, in anembodiment described herein, more particularly provides a single linecontrol module for well tool actuation.

A variety of well tools are available which may be operated or actuatedby application of pressure. For example, a production valve or choke maybe opened or closed by applying pressure to a control line extending toa remote location, such as the earth's surface or another location inthe well. Many other types of well tools and pressure applicationmethods are available, as well.

In instances where a well tool is operated by control line pressure, itis known to use a separate control line for each mode of operation. Forexample, a downhole valve may be opened by increasing pressure on onecontrol line, and the valve may be closed by increasing pressure onanother control line. However, the use of multiple control linesincreases the cost and time required to complete an installation and insome applications, such as subsea wells, the number of control lines orumbilicals is severely limited.

For these reasons, there is a need to reduce the number of control linesused to operate well tools. Some systems have been proposed in the pastwhich use a single control line to operate a downhole well tool.However, for the most part these systems have been unduly complex and,thus, unreliable and expensive.

Therefore, it may be seen that a need exists for improvements inoperating downhole well tools using a single control line.

SUMMARY

In carrying out the principles of the present invention, in accordancewith an embodiment thereof, a single line well tool control system isprovided which satisfies the above need in the art. The system includesa control module which is connected to a well tool actuator, and whichis responsive to pressure in a single control line to control operationof the actuator. The control module is of an uncomplicated and reliabledesign for downhole use.

In one aspect of the invention, a well tool control system is providedwhich includes an actuator and a control module for controlling pressureapplied to the actuator. A single line extends between the controlmodule and a remote location. Elevated pressure is applied to the lineand exhausted from the line at the remote location to operate theactuator.

In another aspect of the invention, a well tool control system isprovided which includes an actuator including first and second chambers,and a line for applying elevated pressure to the actuator to operate theactuator. A control module of the system includes an accumulator, and avalve. The valve has a first position in which the line is connected tothe first chamber and the accumulator is connected to the secondchamber, and a second position in which the line is connected to thesecond chamber and the accumulator is connected to the first chamber.

In a further aspect of the invention, a well tool control system isprovided which includes an actuator including a piston separating firstand second chambers, the actuator operating by relative displacementbetween the piston and the first and second chambers. A control moduleconnects the first chamber to a source of elevated pressure in responseto relative displacement of the piston in a first direction. The controlmodule also connects the second chamber to the source of elevatedpressure in response to relative displacement of the piston in a seconddirection opposite to the first direction.

These and other features, advantages, benefits and objects of thepresent invention will become apparent to one of ordinary skill in theart upon careful consideration of the detailed description ofrepresentative embodiments of the invention hereinbelow and theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic partially cross-sectional view of a well toolcontrol system embodying principles of the present invention;

FIGS. 2-11 are schematic hydraulic circuit diagrams of the system ofFIG. 1, the system being shown in various stages of operation;

FIG. 12 is a schematic hydraulic circuit diagram of the system of FIG. 1with an alternate configuration of the control module;

FIG. 13 is a schematic hydraulic circuit diagram of the system of FIG. 1with a second alternate configuration of the control module; and

FIG. 14 is a schematic hydraulic circuit diagram of the system of FIG. 1with a third alternate configuration of the control module.

DETAILED DESCRIPTION

Representatively illustrated in FIG. 1 is a well tool control system 10which embodies principles of the present invention. In the followingdescription of the system 10 and other apparatus and methods describedherein, directional terms, such as “above”, “below”, “upper”, “lower”,etc., are used for convenience in referring to the accompanyingdrawings. Additionally, it is to be understood that the variousembodiments of the present invention described herein may be utilized invarious orientations, such as inclined, inverted, horizontal, vertical,etc., and in various configurations, without departing from theprinciples of the present invention. The embodiments are describedmerely as examples of useful applications of the principles of theinvention, which is not limited to any specific details of theseembodiments.

As depicted in FIG. 1, a tubular string 12 (such as a production tubingstring or other type of tubing string) has been installed in a wellbore14 which intersects an earth formation 16. Fluids (such as oil and/orgas) from the formation 16 are produced to the surface through thetubular string 12. This flow between the formation 16 and the tubularstring 12 is regulated by means of a well tool 28 interconnected in thetubular string.

The well tool 28 includes a flow control device 18, which may be avalve, in which case flow between an annulus 20 and an interior passage22 of the tubular string 12 may be selectively permitted or prevented byoperation of the valve. The flow control device 18 may alternatively (orin addition) be a choke, in which case the rate of fluid flow betweenthe annulus 20 and the passage 22 may be varied between maximum andminimum limits. These maximum and minimum limits could correspond tofully open and fully closed positions of a closure member 24 of the flowcontrol device 18.

The closure member 24 illustrated in FIG. 1 is configured as a generallytubular sleeve for permitting, preventing and/or otherwise regulatingflow through ports 26 formed through a sidewall of the flow controldevice 18. However, it should be clearly understood that other types ofclosure members (such as plugs, flappers, balls, cages, needles, etc.)may be used in a flow control device without departing from theprinciples of the invention.

It is also not necessary for a flow control device to be used, since theprinciples of the invention may be used in controlling operation ofother types of well tools (such as gravel packing tools, packers,chemical or gas injection tools, perforating tools, drilling tools,etc.). Furthermore, it is not necessary for fluids to be produced from awell using the invention, since fluids could alternatively (or also) beinjected into the well, transferred from one formation to anotherdownhole, etc.

The well tool 28 depicted in FIG. 1 also includes an actuator 30 foroperating the flow control device 18. The actuator 30 is used todisplace the closure member 24 as desired to close or open the ports 26,or to permit a desired rate of fluid flow through the ports. Asillustrated in FIG. 1, the actuator 30 has displaced the closure member24 to a position at which only about half of the flow area of the ports26 is available for flow therethrough.

In one important feature of the invention, the tubular string 12 alsoincludes a control module 32. The control module 32 is preferablyinterconnected between the actuator 30 and a single control line 34extending to a remote location. The control line 34 is depicted in FIG.1 as extending along an exterior of the tubular string 12, but thecontrol line could be completely or partially formed in a sidewall ofthe tubular string, and/or the control line could extend within theinterior passage 22 of the tubular string.

One important benefit of the control module 32 is that it permits thewell tool 28 to be operated using only the single control line 34. Thus,in the example shown in FIG. 1, the closure member 24 may be displaceddownward to close off the ports 26, displaced upward to open the ports,and/or displaced to an intermediate position between fully open andfully closed, using only the single control line 34. Another importantbenefit of the control module 32 is that it is able to accomplish thisresult with a construction that is relatively uncomplicated, reliableand economical.

Although the control module 32 is depicted in FIG. 1 as being separatefrom the actuator 30 and the flow control device 18, it will be readilyappreciated that many other configurations are possible. For example,the control module 32 could be combined with the actuator 30, or thecontrol module actuator and flow control device 18 could be combined inthe well tool 28, etc. Thus, the principles of the invention are notlimited to the specific configurations of the examples illustrated inthe drawings and described here.

Referring now to FIG. 2, a schematic hydraulic circuit diagram isillustrated, showing one possible configuration of the system 10. It maybe seen from FIG. 2 that the control module 32 is made up ofconventional hydraulic circuit components (although uniquely configuredand interconnected to accomplish the objectives of the invention), andas a result the control module can be readily constructed using provenhigh quality, reliable components.

At a lower portion of FIG. 2, components which are connected to thecontrol module 32 via the control line 34 are illustrated. Thesecomponents may be positioned at a surface location or at another remotelocation. The components include a pump 36, a pressure regulator 38, ashuttle valve 40, an input line 42, an exhaust line 44 and a reservoir46. Of course, other components, other types of components and/or othercombinations of components may be used without departing from theprinciples of the invention.

The shuttle valve 40 is illustrated as a manually actuated spring biasedvalve. The valve 40 could be otherwise actuated (such as by pilotpressure, electrical solenoid, etc.) and/or otherwise biased (such asusing gas pressure, unbiased, etc.) in keeping with the principles ofthe invention. As depicted in FIG. 2, the valve 40 is biased toward aposition in which the exhaust line 44 is connected to the control line34, and the input line 42 is closed off at the valve.

In this position of the valve 40, pressure generated by the pump 36 isnot applied to the control line 34, and excess pressure above apredetermined level is bled off from the input line 42 to the reservoir46 by the pressure regulator 38. Any pressure above hydrostatic in thecontrol line 34 is bled off via the exhaust line 44 to the reservoir 46.

Note that the control line 34 presents a significant restriction to flowtherethrough, since the control line may be many hundreds of meterslong, and this is schematically represented by a restrictor 48 in FIG.2. Thus, pressure in the control line 34 is not instantaneously bled offwhen the valve 40 is in the position depicted in FIG. 2. Instead, somesignificant period of time may be required to reduce pressure in thecontrol line 34 to hydrostatic when the valve 40 is moved to theposition shown in FIG. 2.

The actuator 30 is depicted in FIG. 2 at an upper portion of thehydraulic circuit diagram as including a piston 50 in a cylinder 52. Thepiston 50 divides the cylinder 52 into separate chambers 54, 56. Rods58, 60 are connected to the piston 50 and extend outwardly from thecylinder 52.

It should be clearly understood that the actuator 30 as schematicallyillustrated in FIG. 2 is used merely as a representation of any of awide variety of possible actuator configurations which may be used inkeeping with the principles of the invention. It is not necessary for apiston in a cylinder to be used, since many other configurations may bedesirable in certain situations. For example, an annular piston in abore, or another type of actuator may be used. It is also not necessaryfor a piston to displace in the actuator 30, since a piston could remainmotionless while a cylinder or other member displaces relative to thepiston, etc.

When the actuator 30 is connected to the flow control device 18, theclosure member 24 may be connected to one or both of the rods 58, 60, sothat as the piston 50 displaces the closure member also displaces. Ofcourse, the closure member 24 could be connected to another component ofthe actuator 30, such as the cylinder 52, or connected directly to thepiston 50, etc. Any manner of connecting the actuator 30 to the closuremember 24 (or any other component of the well tool 28) may be used inkeeping with the principles of the invention.

As depicted in FIG. 2, the piston 50 is positioned to the left in thecylinder 52. This position of the piston 50 could correspond to a closedposition of the closure member 24, preventing flow through the ports 26.Note that this position of the piston 50 extends the rod 58 outwardly toits maximum extent from the cylinder 52.

In this position of the rod 58, a device 62 carried on the rod depressesa manually actuated spring biased shuttle valve 64 of the control module32. As with the valve 40 described above, the valve 64 may be of anyconfiguration and actuated in any manner in keeping with the principlesof the invention.

The device 62 could be a projection or shoulder formed on, or attachedto, the rod 58 or another component of the actuator 30. For example, ifthe cylinder 52 displaces instead of the piston 50, the device 62 couldbe formed on, or attached to, the cylinder.

It is also not necessary for the device 62 to depress the valve 64. Thedevice 62 could instead be a depression or a recess which allows thevalve 64 to extend when the piston 50 is in the position depicted inFIG. 2. Alternatively, the valve 64 could be magnetically orhydraulically actuated, in which case the device 62 could be, forexample, a magnet, ferrous material or another valve (such as a pilotvalve) used to actuate the valve 64. As other alternatives, the device62 could electrically, thermally, optically or otherwise actuate thevalve 64. Thus, it is preferred that the valve 64 be actuated by acomponent of the actuator 30 when the piston 50 has been fully displacedto the left relative to the cylinder 52, but the specific manner inwhich the valve is actuated can be altered without departing from theprinciples of the invention.

In the position of the valve 64 shown in FIG. 2, a pilot line 66connected to a pilot of a pilot operated shuttle valve 68 is open toflow in both directions through the valve 64. Note, however, that if therod 58 is displaced to the right so that the device 62 no longerdepresses the valve 64, the valve will shift to a position in which flowthrough the pilot line 66 will only be permitted in a direction awayfrom the valve 68 (i.e., pressure cannot be increased in the pilot line66, but pressure can be bled from the pilot line 66).

A separate spring biased pilot operated shuttle valve 70 isinterconnected between the valve 64 and the control line 34. As with theother valves 40, 64, 68 described above, the valve 70 may be any type ofvalve. In the position of the valve 70 depicted in FIG. 2, the pilotline 66 is in communication with the control line 34. Thus, pressure inthe pilot line 66 can be bled off via the valves 64, 70 to the controlline 34.

The valve 70 as shown in FIG. 2 also closes off an accumulator line 72which extends to a pressure accumulator 74. In one important feature ofthe control module 32, the accumulator 74 stores pressure downhole,permitting that pressure to be utilized later, as described in furtherdetail below.

Note that if pressure is applied to a pilot line 76 connected to thevalve 70, the valve will shift to a position in which the pilot line 66will be disconnected from the control line 34, but the pilot line 66will be connected to the accumulator line 72. In this position, flowfrom the pilot line 66 to the accumulator 74 via the accumulator line 72is permitted, but flow in an opposite direction through the valve 70 isprevented. Thus, pressure can be bled from the pilot line 66 to theaccumulator 74 via the valve 70, but pressure cannot be applied to thepilot line from the accumulator in this shifted position of the valve.

The pilot line 76 is connected to the control line 34. Therefore, if thevalve 40 is operated to permit the pump 36 to apply pressure to thecontrol line 34, the valve 70 will shift to connect the pilot line 66 tothe accumulator 74 as described above.

The shuttle valve 68 is dual-pilot operated, having the pilot line 66connected to one side of the valve and another pilot line 78 connectedto an opposite side of the valve. When pressure in the pilot line 66exceeds pressure in the pilot line 78, the valve 68 will be in theposition shown in FIG. 2. In this position, the chamber 54 of theactuator 30 is connected to the control line 34, and the chamber 56 isconnected to an accumulator line 80.

The accumulator line 80 extends from the valve 68 to another pressureaccumulator 82. In another important feature of the invention, theaccumulator 82 is used to store pressure in the control module 32 forlater use in exhausting fluid from the control module through thecontrol line 34, as described in further detail below.

Check valves 84, 86 permit fluid to enter the accumulator 82 only fromthe accumulator line 80, and permit fluid to be exhausted from theaccumulator only to the control line 34. Thus, pressure applied to thecontrol line 34 is not applied to the accumulator 82, even though theaccumulator is connected to the control line via an exhaust line 88.

Note that, if pressure in the pilot line 78 exceeds pressure in thepilot line 66, the valve 68 will shift to a position in which thechamber 56 is connected to the control line 34, and the chamber 54 isconnected to the accumulator line 80. The pilot line 78 is connected toa manually operated spring biased shuttle valve 90 which is similar tothe valve 64. However, the valve 90 is actuated when the piston 50travels to the right, as described below.

In the position shown in FIG. 2, the valve 90 permits pressure in thepilot line 78 to be bled off through the valve, but does not permitpressure to be applied to the pilot line. If the valve 90 is depressed(as shown for the valve 64 in FIG. 2), then pressure may be eitherapplied to or bled off from the pilot line 78 through the valve.

The valve 90 is connected to a pilot operated spring biased shuttlevalve 92. The valve 92 is similar to the valve 70 described above. Apilot line 94 extends from the valve 92 to the control line 34. Anaccumulator line 96 extends from the valve 92 to the accumulator 74.

In the position shown in FIG. 2, the valve 92 connects the pilot line 78to the control line 34. Thus, pressure in the pilot line 78 may be bledoff to the control line 34 through the valve 92. The accumulator line 96is closed off at the valve 92.

However, if elevated pressure exists in the control line 34, thispressure will be applied to the pilot line 94 and the valve 92 willshift to a position in which the pilot line 78 is disconnected from thecontrol line 34 and instead connected to the accumulator line 96. Thevalve 92 in this position will permit pressure to be bled off from thepilot line 78 to the accumulator line 96.

It may now be appreciated that FIG. 2 depicts the system 10 after thepiston 50 has been displaced fully to the left, actuating the valve 64and permitting the pilot line 66 to be in direct communication with thecontrol line 34. Fluid in the accumulator 82 is exhausted via theexhaust line 88, control line 34, valve 40 and exhaust line 44 to thereservoir 46. The accumulator lines 72, 96 are closed off at the valves70, 92.

Referring additionally now to FIG. 3, the system 10 is depicted afterthe valve 40 has been actuated to apply pressure from the pump 36 to thecontrol line 34. The increased pressure in the control line 34 iscommunicated to the pilot lines 76, 94. This shifts the valves 70, 92 topositions in which the pilot lines 66, 78 are connected to theaccumulator 74.

Note, however, that the control module 32 includes a restrictor 98 inthe control line 34. The restrictor 98 is positioned between theconnection between the control line 34 and the pilot lines 76, 94, andthe connection between the control line and lines 100, 102 extending tothe valves 70, 92. The lines 100, 102 are in communication with therespective pilot lines 66, 78 prior to the valves 70, 92 shifting inresponse to increased pressure in the control line 34. That is, therestrictor 98 ensures that increased pressure in the control line 34 isapplied to the appropriate one of the pilot lines 66, 78 prior to thevalves 70, 92 shifting in response to increased pressure in the pilotlines 76, 94.

Note that in FIG. 2 the pilot line 66 is in direct communication withthe control line 34 via the valves 64, 70 and line 100. However, a checkvalve in the valve 90 prevents pressure applied to the control line 34from being communicated to the pilot line 78. Thus, as pressure isincreased in the control line 34, greater pressure will exist in thepilot line 66 than in the pilot line 78, thereby maintaining the valve68 in its position as shown in FIG. 2.

Eventually, the restrictor 98 will permit sufficient pressure to buildup in the control line 34 and the pilot lines 76, 94 downstream of therestrictor to shift the valves 70, 92 to their positions as depicted inFIG. 3. In these positions of the valves 70, 92, pressure in the pilotlines 66, 78 may bleed off to the accumulator lines 72, 96.

With the valve 68 in the position shown in FIG. 3, increased pressure inthe control line 34 is communicated to the chamber 54 of the actuator30, thereby displacing the piston 50 to the right. This displacement ofthe piston 50 may be used to displace the closure member 24 of the flowcontrol device 18 upward to partially open the ports 26. Displacement ofthe piston 50 could be halted at this point (by shifting the valve 40back to its FIG. 2 position) to leave the closure member 24 between itsfully open and fully closed positions, thereby choking the flow throughthe ports 26, if desired.

As the piston 50 displaces to the right, fluid in the chamber 56 isdischarged from the cylinder 52 and through the valve 68 into theaccumulator line 80. This fluid passes through the check valve 84 andinto the accumulator 82, thereby pressurizing the accumulator. The checkvalve 86 prevents the increased pressure in the control line 34 frompressurizing the accumulator 82.

Displacement of the piston 50 to the right also displaces the rod 58,causing the device 62 to no longer depress the valve 64. Pressure maynow be bled off from the pilot line 66, but pressure may not be appliedto the pilot line 66 through the valve 64.

Referring additionally now to FIG. 4, the system 10 is depicted as thepiston 50 approaches its fully stroked position to the right. A device104 carried on the rod 60, similar to the device 62 described above,depresses the valve 90. As with the device 62, the device 104 mayactuate the valve 90 in any manner, including mechanically,hydraulically, magnetically, electrically, optically, thermally, etc.Fluid in the chamber 56 continues to flow into the accumulator 82 viathe valve 68, accumulator line 80 and check valve 84, furtherpressurizing the accumulator.

Referring additionally now to FIG. 5, the system 10 is depicted with thepiston 50 at its fully stroked position to the right. This position ofthe piston 50 may correspond to a fully open position of the closuremember 24 in the flow control device 18. The accumulator 82 is fullycharged at this point.

Referring additionally now to FIG. 6, the system 10 is depicted with thevalve 40 shifted to disconnect the control line 34 from the input line42 and exhaust fluid from the control line to the reservoir 46 via theexhaust line 44. The fluid stored in the pressurized accumulator 82 isexhausted via the check valve 86 and exhaust line 88 to the control line34.

It may now be fully appreciated how the accumulator 82 operates toassist in exhausting fluid from the control module 32 and displacing thefluid up the control line 34. In this manner, the fluid does not have tobe dumped to the annulus 20 or interior passage 22 downhole wherehydrostatic and flowing pressures fluctuate or may be unknownbeforehand, and where debris would have an opportunity to enter thecontrol module 32.

In basic terms, operation of the actuator 30 pressurizes the accumulator82 using fluid discharged from the actuator. Later, after the actuator30 has been operated to a desired position, the fluid stored in theaccumulator 82 is exhausted through the control line 34 using the storedpressure.

It may also now be fully appreciated how the single control line 34 isused both for delivering fluid and applying pressure to the actuator 30,and for exhausting fluid and pressure from the actuator. The use of thecontrol line 34 in this manner reduces the number of control lines orumbilicals needed for a well, decreasing the expense of the system 10installation, reducing the time required for the installation,decreasing the chances of a leak occurring in multiple lines, etc.

Referring additionally now to FIG. 7, the system 10 is depicted afterthe elevated pressure in the control line 34 has been fully exhausted.This also relieves the elevated pressure in the pilot lines 76, 94, andso the valves 70, 92 are shifted back to positions in which directcommunication is provided through the valves between the respectivelines 100, 102 and pilot lines 66, 78. However, the valve 64 still onlypermits pressure to be bled off of the pilot line 66, while the valve 90permits pressure to be applied to the pilot line 78.

Referring additionally now to FIG. 8, the system 10 is depicted with thevalve 40 shifted to connect the input line 42 to the control line 34,thereby applying increased pressure from the pump 36 to the controlline. With the valve 92 positioned as shown in FIG. 7, this increasedpressure is applied to the pilot line 78 via the line 102, valve 92 andvalve 90, thereby shifting the valve 68. Pressure in the pilot line 66is not increased due to a check valve in the valve 64.

The restrictor 98 delays application of the increased pressure to thepilot lines 76, 94 until after the valve 68 has shifted. When sufficientpressure is applied to the pilot lines 76, 94, the valves 70, 92 areshifted to their positions shown in FIG. 8.

With the valve 68 shifted to the position shown in FIG. 8, increasedpressure in the control line 34 is communicated to the chamber 56 of theactuator 30, thereby displacing the piston 50 to the left. This leftwarddisplacement of the piston 50 may be used to displace the closure member24 so that a reduced rate of flow is permitted through the ports 26.Displacement of the piston 50 may be halted at any time (by shifting thevalve 40 back to the position shown in FIG. 7) to position the closuremember 24 as desired relative to the ports 26, for example, to permit adesired rate of flow through the ports.

This displacement of the piston 50 to the left causes fluid in thechamber 54 to be discharged from the cylinder 52 and through the valve68, accumulator line 80 and check valve 84 to the accumulator 82. Thus,the accumulator 82 is pressurized as the piston 50 displaces to theleft. Note that the accumulator 82 is pressurized with fluid dischargedfrom the cylinder 52 both when the piston displaces to the left (asdepicted in FIG. 8) and when the piston displaces to the right (asdepicted in FIG. 3).

Referring additionally now to FIG. 9, the system 10 is depicted afterthe piston 50 has displaced sufficiently far to the left that the device104 no longer depresses the valve 90. Both of the valves 64, 90 are nowpositioned so that the respective pilot lines 66, 78 may be bled off tothe accumulator 74 via the accumulator lines 72, 96, but pressure maynot be applied to either of the pilot lines.

Referring additionally now to FIG. 10, the system 10 is depicted withthe piston 50 displaced to its fully stroked left position. The device62 again depresses the valve 64, permitting pressure to be applied tothe pilot line 66 through the valve. However, the valve 70 still permitsonly flow of fluid from the pilot line 66 to the accumulator line 72.

Referring additionally now to FIG. 11, the system 10 is depicted withthe valve 40 shifted to disconnect the input line 42 from the controlline 34, and to exhaust fluid and pressure from the control line to thereservoir 46 via the exhaust line 44. Fluid and pressure stored in theaccumulator 82 may now be exhausted to the control line 34 via the checkvalve 86 and exhaust line 88. Thus, fluid and pressure are exhaustedfrom the accumulator 82 both after the piston 50 has displaced to theleft, and after the piston has displaced to the right.

As shown in FIGS. 2-11, the piston 50 has been displaced to the rightand then back to the left by merely shifting the valve 40 back andforth. As described above, this displacement of the piston 50 may beused to displace the closure member 24 of the flow control device 18 toits fully open and fully closed positions, and to a position between thefully open and fully closed positions. Alternatively, displacement ofthe piston 50 may be used to operate other types of well tools. Forexample, instead of or in addition to the flow control device 18, thewell tool 28 could include a sampler, pump, sensor, perforating device,packer, oil/water separator or other type of well tool operable bydisplacement of the piston 50.

Between each displacement of the piston 50, fluid stored in theaccumulator 82 has been exhausted back to the reservoir 46 via thecontrol line 34. The control line 34 is used alternately to deliverfluid to the actuator 30 to displace the piston 50 to the right and todisplace the piston to the left, and to exhaust fluid from the actuatorafter the piston has displaced to the left and after the piston hasdisplaced to the right.

The piston 50 may be displaced again to the right from its positiondepicted in FIG. 11 by shifting the valve 40 to place the input line 42in communication with the control line 34. Increased pressure applied tothe control line 34 by the pump 36 will then be communicated to thepilot line 66, thereby shifting the valve 68 so that the control line isplaced in communication with the chamber 54. Then, increased pressure inthe pilot lines 76, 94 will cause the valves 70, 92 to shift, and thesystem will be returned to the configuration depicted in FIG. 3 as thepiston 50 displaces to the right. Thus, the system 10 permits the piston50 to be displaced back and forth repeatedly as many times as isdesired.

Referring additionally now to FIG. 12, the system 10 is depicted in analternate configuration. This alternate configuration is similar to thesystem 10 as illustrated in FIGS. 2-11, except that a volume meteringdevice 112 has been interconnected in the control module 32.

The volume metering device 112 enables the piston 50 to be incrementallydisplaced in the actuator 30. For example, an application of elevatedpressure to the control line 34 (by shifting the valve 40 to theposition shown in FIG. 12) will cause the elevated pressure to beapplied to the device 112. In response, the device 112 discharges apredetermined volume of fluid to the chamber 54 via the valve 68,thereby displacing the piston 50 to the right a predetermined distance.

Alternatively, the device 112 may permit a predetermined volume of fluidto be discharged from the chamber 56 in response to the application ofelevated pressure to the control line 34. Again, the piston 50 would bedisplaced to the right a predetermined distance.

If the device 112 is configured to discharge the predetermined volume offluid to the chamber 54 in response to elevated pressure applied to thecontrol line 34, then the device may only be interconnected in thecontrol line 34, without also being interconnected in the accumulatorline 80 as depicted in FIG. 12, and the accumulator line may beconnected directly to the valve 68. Similarly, if the device 112 isconfigured to permit discharge of the predetermined volume of fluid fromthe chamber 56 in response to elevated pressure applied to the controlline 34, then the device may only be interconnected in the accumulatorline 80, without also being interconnected in the control line 80 asdepicted in FIG. 12, and the control line may be connected directly tothe valve 68.

By repeatedly applying elevated pressure to the control line 34 (e.g.,by shifting the valve 40 back and forth), the predetermined volume offluid may be repeatedly discharged to the chamber 54 from the device112, or repeatedly discharged from the chamber 56 via the device 112, asmany times as desired to produce a corresponding number of incrementaldisplacements of the piston 50 to the right. This feature may be useful,for example, in accurately adjusting the position of the closure member24 to produce a known flow area through the ports 26 or a known pressuredrop across the ports, etc.

When the piston 50 has displaced fully to the right and the valve 68 hasbeen shifted by pressure applied to the control line 34 (similar to theconfiguration depicted in FIG. 8), then the device 112 will operate todischarge the predetermined volume of fluid to the chamber 56, or topermit the predetermined volume of fluid to be discharged from thechamber 54. Again, the elevated pressure may be applied to the controlline 34 repeatedly to produce a desired number of incrementalpredetermined displacements of the piston 50 to the left. Thus, by usingthe device 112 in the control module 32, incremental predetermineddisplacements of the piston 50 to the right and to the left may beaccomplished.

The device 112 may be any type of volume metering device. For example,any of the devices described in U.S. Pat. No. 6,585,051 may be used,e.g., to discharge a predetermined volume of fluid from the control line34 to the chamber 54 or chamber 56 of the actuator 30. As anotherexample, the device described in U.S. application Ser. No. 10/643,488filed Aug. 19, 2003 may be used, e.g., to permit discharge of apredetermined volume of fluid from the chamber 54 or chamber 56 of theactuator 30 to the accumulator line 80. The entire disclosures of theU.S. patent and application mentioned above are incorporated herein bythis reference.

Referring additionally now to FIG. 13, the system 10 is depicted inanother alternate configuration. This alternate configuration is similarin many respects to the other configurations described above, and sosimilar components are indicated in FIG. 13 using the same referencenumbers.

As with the configuration depicted in FIG. 12, the volume meteringdevice 112 is used in the configuration depicted in FIG. 13 to regulatethe volume of fluid transferred between the control module 32 and theactuator 30. In this case, the volume metering device 112 is used tometer the volume of fluid discharged from the chamber 56 of theactuator. That is, each time elevated pressure is applied via thecontrol line 34 and volume metering device 112 to the chamber 54, thevolume metering device permits only a predetermined volume of fluid tobe discharged from the chamber 56, thereby causing the piston 50 todisplace a predetermined incremental distance upward as viewed in FIG.13.

In this manner (i.e., permitting discharge of a predetermined volume offluid from an actuator in response to each of multiple pressureapplications to the actuator), the volume metering device 112 asdepicted in FIG. 13 is similar to the volume metering device describedin the U.S. application Ser. No. 10/643,488 referred to above. However,other types of volume metering devices (such as any of the volumemetering devices described in U.S. Pat. No. 6,585,051) may be used inkeeping with the principles of the invention.

As depicted in FIG. 13, the control line 34 is vented to the reservoir46 by the valve 40. To operate the actuator 30, the valve 40 is actuatedto connect the input line 42 to the control line 34, thereby applyingelevated pressure from the pump 36 to the control line. The elevatedpressure is applied to the chamber 54 of the actuator 30 via a valve114, a line 116 connected between the valve and the volume meteringdevice 112, and another line 118 connected between the volume meteringdevice and the actuator.

The elevated pressure is transmitted via the piston 50 to the otherchamber 56 of the actuator 30. The chamber 56 is connected to the volumemetering device 112 via another line 120. The volume metering device 112permits a certain volume of fluid to be discharged from the line 120(and, thus, from the chamber 56) to another line 122 connected betweenthe volume metering device and the valve 114. As the volume of fluid isdischarged from the chamber 56, the piston 50 displaces upward a knownincremental distance.

The fluid discharged into the line 122 is used to charge the accumulator82 via the valve 114 and the check valve 84. When the valve 40 isreturned to its position as shown in FIG. 13, elevated pressure storedin the accumulator 82 is vented to the reservoir 46 via the check valve86 and control line 34.

This completes one cycle of incremental upward displacement of thepiston 50. Additional upward displacements of the piston 50 may beperformed by alternately applying elevated pressure to the control line34, and then venting the control line as described above.

Note that an accumulator 124 is connected to a pilot line 126 of thevalve 114. The pilot line 126 is connected to the line 116 via aparallel-connected check valve 128 and restrictor 130. When elevatedpressure is applied to the line 116 (such as when the piston 50 is beingdisplaced upward as described above), the check valve 128 permitsunimpeded flow from the line 116 to the pilot line 126. This acts tocharge the accumulator 124 and maintain the valve 114 in the position asshown in FIG. 13.

When pressure in the line 116 is vented (such as when the control line34 is vented after displacement of the piston 50), the restrictor 130delays venting of the pressure in the pilot line 126. This acts tomaintain the valve 114 in the position as shown in FIG. 13 until afterthe control line 34 has been fully vented. The accumulator 124 aids inmaintaining elevated pressure in the pilot line 126.

Another accumulator 134, check valve 136 and restrictor 138 aresimilarly connected between another pilot line 140 of the valve 114 andthe line 122. The accumulator 134, check valve 136 and restrictor 138serve a purpose similar to that of the accumulator 124, check valve 128and restrictor 130 described above, in that they delay venting ofelevated pressure on the pilot line 140.

Another restrictor 132 connected between the control line 34 and thevalve 114 ensures that pressure venting from the line 116 is delayedrelative to pressure venting from the line 122. Thus, when elevatedpressure has been applied to the control line 34 to displace the piston50 incrementally upward, the accumulator 124 will be charged by thepressure in the line 116, the accumulator 134 will be charged by thepressure in the line 122, and the accumulator 82 will be charged by thepressure in the line 80 (which should be the same as the pressure in theline 122, but which may be somewhat less than the pressure in the line116).

The two sets of accumulators 124, 134, check valves 128, 136 andrestrictors 130, 138 form two respective time delay circuits which servepurposes in addition to those described above. The time delay circuitsallow the volume metering device 112 to “recock” at the conclusion ofeach pressure application cycle. In addition, the time delay circuitstemporarily maintain back pressure on the restrictor 132, so that theaccumulator 82 will discharge fluid through the control line 34 towardthe reservoir 46.

When the piston 50 has been displaced upward a sufficient distance, thedevice 104 will engage the valve 114. When the control line 34 pressureis subsequently reduced and the time delay circuits have bled off theincreased pressure, valve 114 will shift and to a position in which thecontrol line 34 is connected to the line 122, and the accumulator line80 is connected to the line 116.

When the valve 40 is then actuated to vent the control line 34, the line122 will be vented via the valve 114 and the restrictor 132. Theaccumulator 82 will be vented (along with the accumulator line 80 andline 116 via the valve 114) via the check valve 86 to the control line34. Note that the venting of the line 122 will now be delayed relativeto venting of the line 116, thereby ensuring that pressure in the pilotline 140 remains elevated relative to pressure in the pilot line 126,and thus maintaining the valve 114 in its shifted position.

The valve 40 can then be actuated to connect the input line 42 to thecontrol line 34 and thereby apply elevated pressure to the line 122 viathe valve 114. When pressure in the line 122 is greater than pressure inthe line 116, the volume metering device 112 permits an unlimited volumeof fluid to be discharged to the line 120. Thus, the piston 50 will bedisplaced to its fully downward stroked position in response to theapplication of elevated pressure to the line 122.

As the piston 50 strokes downward, fluid is discharged from the chamber54 to the line 118. This fluid is used to charge the accumulator 82 viathe line 116, valve 114 and accumulator line 80. When the valve 40 isreturned to its position as shown in FIG. 13 to vent the control line34, pressure stored in the accumulator 82 will be vented to the controlline via the check valve 86.

The lines 116, 122 will also be vented when the control line 34 isvented. The restrictor 132 will ensure that the pressure in the line 122remains elevated relative to that in the line 116 as the lines are beingvented. In addition, the accumulator 134 will maintain a somewhatgreater pressure on the pilot line 140 as compared to that maintained onthe pilot line 126 by the accumulator 124, thereby ensuring that thevalve remains in its shifted position as the lines 116, 122 are beingvented.

Eventually, the lines 34, 80, 116, 122 will be fully vented. At thatpoint (or just prior), a biasing device 142 will shift the valve 114back to its initial position as shown in FIG. 13. The system 10 is thenready to again incrementally displace the piston 50 upward byalternately applying elevated pressure to, and venting, the control line34 by actuating the valve 40 back and forth.

It may now be fully appreciated that the actuator 30 may be convenientlyoperated using the control module 32 and only a single control line 34extending to the valve 40 at the remote location. The piston 50 may beincrementally displaced upward (for example, to position a downholechoke so that a desired flow rate or pressure drop is achieved) byalternately applying and venting elevated pressure on the control line34. The actuator 30 may be reset (i.e., the piston 50 displaced back toits fully stroked downward position) by displacing the piston to itsfully upward stroked position, venting the control line 34, and thenapplying elevated pressure to the control line to stroke the pistonfully downward, and again venting the control line. At that point, thepiston 50 can again be incrementally displaced upward by alternatelyapplying and venting elevated pressure on the control line 34.

Referring additionally now to FIG. 14, the system 10 is depicted inanother alternate configuration. This alternate configuration is similarin many respects to the other configurations described above, and sosimilar components are indicated in FIG. 14 using the same referencenumbers.

The configuration depicted in FIG. 14 is most similar to theconfiguration depicted in FIG. 13, in that the volume metering device112 is used to permit discharge of a predetermined volume of fluid fromthe chamber 56 when increased pressure applied to the control line 34displaces the piston 50 upward. However, one difference is thatactuation of the valve 114 in the configuration shown in FIG. 14 is notdependent at all upon displacement of the piston 50. Instead, the valve114 is biased toward the position shown in FIG. 14, and is also pilotoperated by pressures in the pilot lines 126, 140. Thus, pressure in thepilot line 140 must exceed pressure in the pilot line 126 by apredetermined amount for the valve 114 to shift from its position shownin FIG. 14.

The piston 50 is at its lowermost position as depicted in FIG. 14. Todisplace the piston 50 incrementally upward, the valve 40 is shifted toapply pressure from the pump 36 to the control line 34. Elevatedpressure in the control line 34 is communicated to the accumulator 134via lines 144, 146 and a spring biased pilot operated valve 148. Theaccumulator 134 stores this elevated pressure therein.

Note that, at this point the valve 114 is in a position such that theelevated pressure in the control line 34 is communicated to the line122, which communicates with the actuator chamber 56 via the volumemetering device 112 and line 120. The elevated pressure in the controlline 34 is also communicated to the line 116 (which communicates withthe actuator chamber 54 via the volume metering device 112 and line 118)via the line 144 and another line 150. However, restrictor 138 in theline 150, and another restrictor 152 in the line 144 delay pressurebuildup in the line 116 relative to that in the line 122, and so thepiston 50 is not permitted to displace upward.

The valve 40 is then shifted to bleed off the control line 34 to thereservoir 46. The restrictor 152 delays the venting of pressure from theaccumulator 134. The pilot line 140 is connected to the accumulator line146 via the valve 148, and so this delay in venting pressure from theaccumulator 134 causes pressure in the pilot line 140 to exceed pressurein the pilot line 126 by an amount sufficient to shift the valve 114.

Thus, upon venting the control line 34 the valve 114 is shifted and thecontrol line 34 is placed in communication with the line 116 via thevalve 114. The valve 40 may then be shifted to again apply elevatedpressure to the control line 34, which will be communicated via thevolume metering device 112 to the chamber 54, causing the piston 50 todisplace upward, and causing a predetermined volume of fluid to bedischarged from the chamber 56 via the volume metering device to theline 122. Fluid discharged from the chamber 56 is communicated to theaccumulator 82 via the lines 122, 80, valve 114 and check valve 84.

The valve 40 may be shifted alternately back and forth to alternatelyvent and apply elevated pressure to the control line 34 and therebyincrementally displace the piston 50 upward. As the piston 50 displacesupward, fluid discharged from the chamber 56 pressurizes the accumulator82 via the line 122, valve 114, line 80 and check valve 84. Thisincreased pressure in the accumulator line 80 is also communicated to apilot line 154 of the valve 148, thereby shifting the valve so that thepilot line 140 is disconnected from the line 144 and placing a checkvalve of the valve 148 between the accumulator line 146 and the pilotline 140. Thus, pressure in the pilot line 140 is prevented frombleeding off sufficiently for the valve 114 to shift back to itsposition as depicted in FIG. 14 as the valve 40 is shifted alternatelyback and forth to displace the piston 50 incrementally upward.

Eventually, the piston 50 will reach its uppermost position. At thispoint, the valve 40 will be shifted to vent the control line 34 to thereservoir 46.

After a sufficient amount of time, the accumulators 82, 134 will becompletely bled off via the control line 34. When the pressure in thepilot line 140 is no longer sufficiently greater than the pressure inthe pilot line 126, the valve 114 will shift back to its position asshown in FIG. 14. Note that in this position the control line 34 isagain placed in communication with the line 122 via the valve 114.

The valve 40 is then shifted to place the pump 36 in communication withthe control line 34, thereby applying elevated pressure to the controlline. This elevated pressure is transmitted to the line 122, through thevolume metering device 112, through the line 120 and to the chamber 56.The piston 50 is thereby displaced downward to its position asillustrated in FIG. 14.

Fluid discharged from the chamber 54 as the piston 50 displaces downwardpressurizes the accumulator 82 via the line 118, volume metering device112, line 116, valve 114, line 80 and check valve 84. This increasedpressure in the accumulator line 80 is also communicated to the pilotline 154 of the valve 148, thereby shifting the valve so that the pilotline 140 is disconnected from the line 144 and placing a check valve ofthe valve 148 between the accumulator line 146 and the pilot line 140.This prevents increased pressure from being applied to the pilot line140 and thereby prevents the valve 114 from shifting as the piston 50displaces downward.

When the valve 40 is then shifted to vent the control line 34 to thereservoir 46, the pressure stored in the accumulator 82 is vented viathe check valve 86 to the control line. As pressure in the line 154bleeds off, the valve 148 shifts back to its position as illustrated inFIG. 14, thereby allowing the accumulator 134 to be vented to thecontrol line 34 also.

Thus, the piston 50 has completed a complete cycle described above ofdisplacing incrementally upward, and then displacing downward back toits initial position as depicted in FIG. 14. Of course, the hydrauliccircuit could be modified so that the piston 50 displaces incrementallydownward (or in any other direction, such as leftward or rightward,etc.) instead of incrementally upward. For example, the valve 114 couldbe reversed, so that the control line 34 is placed in communication withthe line 116 when the system is completely vented.

Furthermore, any other volume metering device could be used in place ofthe device 112 shown in FIG. 14. In addition, it is not necessary forthe volume metering device 112 to be used at all, for example, if it isnot desired to incrementally displace the piston 50, in which case theline 116 could be connected directly to the line 118 and the line 122could be connected directly to the line 120.

Note that if the piston 50 is midway between its uppermost and lowermostpositions when the control line 34 is vented completely and theaccumulators 82, 134 are completely bled off to hydrostatic pressure,then when elevated pressure is again applied to the control line 34 (byshifting the valve 40), the piston 50 will initially displace downwardsomewhat (since the valve 114 will connect the control line 34 to theline 122). However, as soon as pressure in the pilot line 140 increasessufficiently to shift the valve 114, the piston 50 can continue itsincremental upward displacement in response to alternately shifting thevalve 40 back and forth to alternately pressurize and vent the controlline 34 as described above.

A restrictor 156 in the pilot line 140 between the valves 114 and 148functions to delay venting or bleed off of the line, thereby maintainingelevated pressure in the line for an extended time. In this manner, thepilot line 140 can be charged at any time in the actuation cycle, andwhen the control line 34 is vented the pilot line 140 venting isdelayed. This allows the valve 114 to be switched (with an appropriatetime delay), so the actuator 30 can be properly operated.

A restrictor 158 in the pilot line 154 between the accumulator line 80and the valve 148 functions to delay switching of the valve as pressurein the line increases. This prevents undesirable switching back andforth of the valve 148 when the pilot line 154 is at approximately thepressure required to actuate the valve. The restrictor 158 also ensuresthat the pilot line 140 and accumulator 134 are sufficiently pressurizedbefore the valve 148 switches, so that switching of the valve 114 isconsistent.

Note that additional restrictors, valves, accumulators, etc. could beincluded in any of the hydraulic circuits described above as desired torefine their operation. Furthermore, other circuit elements orcombinations of elements could be substituted for those described above,without departing from the principles of the invention.

Of course, a person skilled in the art would, upon a carefulconsideration of the above description of representative embodiments ofthe invention, readily appreciate that many modifications, additions,substitutions, deletions, and other changes may be made to the specificembodiments, and such changes are contemplated by the principles of thepresent invention. Accordingly, the foregoing detailed description is tobe clearly understood as being given by way of illustration and exampleonly, the spirit and scope of the present invention being limited solelyby the appended claims and their equivalents.

1. A well tool control system, comprising: an actuator; a control modulefor controlling pressure applied to the actuator; and a single lineextending between the control module and a remote location, elevatedpressure being applied to the line and exhausted from the line at theremote location to operate the actuator.
 2. The system of claim 1,wherein the actuator includes a piston separating first and secondchambers, the first chamber being connected to the line and the secondchamber being connected to an accumulator of the control module whenelevated pressure is applied to the line to displace the piston relativeto the first and second chambers in a first direction, and the secondchamber being connected to the line and the first chamber beingconnected to the accumulator when elevated pressure is applied to theline to displace the piston relative to the first and second chambers ina second direction opposite to the first direction.
 3. The system ofclaim 2, wherein fluid stored in the accumulator is exhausted to theline when elevated pressure is exhausted from the line at the remotelocation.
 4. The system of claim 2, wherein pressure in the accumulatoris bled off to the line when elevated pressure is exhausted from theline at the remote location.
 5. The system of claim 2, wherein thecontrol module further includes a first valve which alternately connectsthe first and second chambers to the accumulator.
 6. The system of claim5, wherein the first valve is operated in response to pressure in theline.
 7. The system of claim 5, wherein the control module furtherincludes a second valve connected to a pilot line of the first valve. 8.The system of claim 7, wherein the second valve is operated in responseto displacement of the piston relative to the first and second chambers.9. A well tool control system, comprising: an actuator including firstand second chambers; a line for applying elevated pressure to theactuator to operate the actuator; and a control module including anaccumulator, and a first valve having a first position in which the lineis connected to the first chamber and the accumulator is connected tothe second chamber, and a second position in which the line is connectedto the second chamber and the accumulator is connected to the firstchamber.
 10. The system of claim 9, wherein the system includes only thesingle line connected between the control module and a remote location.11. The system of claim 10, wherein the line is used both for applyingelevated pressure to the actuator and for exhausting fluid from theaccumulator.
 12. The system of claim 9, wherein the actuator furtherincludes a piston separating the first and second chambers, and whereinthe piston displaces in a first direction relative to the first andsecond chambers when the first valve is in the first position, and thepiston displaces in a second direction opposite to the first directionrelative to the first and second chambers when the first valve is in thesecond position.
 13. The system of claim 9, wherein fluid from thesecond chamber is discharged to the accumulator when elevated pressureis applied to the first chamber, and wherein fluid from the firstchamber is discharged to the accumulator when elevated pressure isapplied to the second chamber.
 14. The system of claim 13, wherein fluidis discharged from the accumulator to the line when elevated pressure isnot applied to the line.
 15. The system of claim 9, wherein the controlmodule further includes a second valve connected to a pilot line of thefirst valve, the second valve being operated in response to displacementof a piston of the actuator relative to the first and second chambers.16. A well tool control system, comprising: an actuator including apiston separating first and second chambers, the actuator operating byrelative displacement between the piston and the first and secondchambers; and a control module which connects the first chamber to asource of elevated pressure in response to relative displacement of thepiston in a first direction, and which connects the second chamber tothe source of elevated pressure in response to relative displacement ofthe piston in a second direction opposite to the first direction. 17.The system of claim 16, wherein a single line connects the source ofelevated pressure to the control module.
 18. The system of claim 17,wherein the line is used to alternately exhaust fluid from the controlmodule and apply elevated pressure to the control module.
 19. The systemof claim 16, wherein the first chamber is connected to an accumulator ofthe control module when the second chamber is connected to the source ofelevated pressure, and wherein the second chamber is connected to theaccumulator when the first chamber is connected to the source ofelevated pressure.
 20. The system of claim 16, wherein the controlmodule further includes a volume metering device which causes anincremental relative displacement of the piston in response to each ofmultiple elevated pressures being applied to the control module.